Acute myeloid leukemia (AML) is a life-threatening disorder in which certain blood cells become cancerous and rapidly replace normal cells in the bone marrow. As normal blood cells are replaced by cancerous cells, people with AML become anemic from too few red blood cells. They develop infections easily because there are too few white blood cells to fight infections, and their blood does not clot well because of too few platelets. Which of the following additional symptoms of AML may be caused by having too few white blood cells?